Over the course of 20 years of representing driving-under-the-influence defendants, I developed a paradigm to evaluate DUI cases. After interviewing every DUI defendant, I ask myself: "Why is this case different from all other DUI cases?"

The term DUI includes both driving while intoxicated (DWI, a misdemeanor or felony) and driving while impaired (DWAI, a traffic infraction or misdemeanor). This column describes a typical arrest for driving under the influence, but does not address repeat offenders, commercial drivers or underage drivers.

An arrest unfolds

After I told a young man at an intake interview how a DUI arrest usually occurs, he exclaimed: "Man, it's like you were there!"

Typically, someone has had some drinks and is driving home. Usually, they see red flashing lights behind them and mutter something like "Aw, heck!"

Sometimes, the officer testifies favorably that the motorist responded by pulling over promptly and safely. In other cases, the officer testifies that there was a delay in the motorist responding or a violation of the Vehicle and Traffic Law.

Usually, the officer pulls up behind the motorist's vehicle parked on the shoulder of the road and comes to the window. The first words out of the officer's mouth are something like, "License and registration!" or "Do you know why I've stopped you?"

Sometimes, the officer testifies favorably that the motorist produced the license and registration without any difficulty. In other cases, the officer testifies that the motorist was fumbling, mumbling and confused. The officer invariably testifies to observations of "slurred speech, bloodshot, watery eyes and the odor of an alcoholic beverage." The officer then asks the motorist, "Have you been drinking?" Usually the motorist answers "A few" or "A couple." If the motorist admits to drinking, the officer will request that field sobriety tests (FSTs) be performed. They often commence inside the car with tests like the alphabet test and the finger-count test.

Outside of the car, the following FSTs are commonly administered: the horizontal-gaze nystagmus, the one-legged stand, and the walk and turn.

Any motorist found driving who has admitted to drinking and who does not pass all these tests will be asked to blow into a portable breath tester (PBT, also known as an Alcosensor).

Unless the person passes all of these tests, the officer will announce, "You are under arrest for DWI. Put your hands behind your back." The motorist will be handcuffed and told that the car will be towed and that he or she will be taking a trip to the police station for a Breathalyzer test.

The Breathalyzer

Thereafter, the officer will ask whether the motorist consents or refuses to take the Breathalyzer test at the station. The motorist is warned that if refused, her or his driver's license will be revoked, regardless of the outcome of the charges in criminal court.

Some motorists take the test without hesitation and the result is recorded. Other motorists refuse to take the test without hesitation and are written up as having refused. When asked to consent or refuse, some motorists "hem-and-haw" or ask to speak to an attorney. Unless the motorist consents or refuses to take the Breathalyzer within approximately 20 minutes, the officer becomes peevish and says something like: "Are you gonna take the test or not? I need an answer now!"

Motorists may not condition their consent upon speaking with an attorney. Most attempts to contact an attorney are futile because such arrests are typically made in the wee hours of the morning.

After taking or refusing the test, the motorist will be booked (photographed and fingerprinted) before release with copies of tickets directing where and when to appear in court.

The charges typically include at least one moving violation (the reason for the traffic stop), such as failure to keep right, and a charge of driving while intoxicated based on physical condition (so-called "common law" DWI).

BAC ranges

The blood-alcohol concentration (BAC) determines the DUI per se charge:

• DWAI (driving while ability impaired): more than .05 percent, but less than .08.

• DWI: 08 percent or more.

• ADWI (aggravated DWI): .18 percent or more.

A motorist charged with DWI who has a DWI conviction within the past 10 years will be prosecuted for felony DWI.

Although a PBT provides a percentage BAC estimation (as does a Breathalyzer) PBT results are inadmissible at trial. Under New York's implied-consent law, it is unlawful for any operator to refuse a PBT. It is not unlawful to refuse a Breathalyzer, but any chemical-test refusal results in automatic license revocation and civil penalties. It may also be admissible at a DUI trial as evidence of "consiousness of guilt."

Most people could not pass the FST balance-and-coordination and divided-attention tests even if "sober as a judge." The alphabet and finger-count tests are neither standardized nor approved by the National Highway Traffic Safety Administration. The only standardized FSTs are the horizontal-gaze nystagmus, one-legged stand, and walk and turn. These FSTs are rated, respectively, as 77 percent, 65 percent and 68 percent reliable by the NHTSA under ideal test conditions. When administered under less-than-ideal conditions, the NHTSA considers these tests mere "indicators of impairment."

Usually, the tests are performed in darkness on a roadside shoulder, with cars passing and police lights flashing as the officer scowls at the nervous motorist. The horizontal-gaze nystagmus test is not designed to measure ability to operate a motor vehicle but, rather, to estimate BAC. There are 38 medical causes of horizontal-gaze nystagmus, one of which is impairment by alcohol.

I always try to assess whether the officer will describe the defendant as polite and cooperative. That is not a basis for dismissal, but in many cases it has helped avoid a DWI conviction. The climax of my cross-examination in a recent DWI trial was asking the arresting officer: "Isn't it true that if my client was a man you would describe her as a gentleman?"

The variations

Variations of the common DUI arrest scenario are infinite, but here are some common ones:

• The motorist was not "pulled over," but found at the scene of an accident. In such cases, the identity of the operator might be the basis of an "operation defense." Admissions of operation must be corroborated, but may be corroborated by circumstantial evidence. If the motorist was involved in an accident, it may be impossible for the prosecutor to prove that the FST failure was caused by alcohol or the accident. In many accident cases, FSTs are not administered for this reason.

Checkpoints are designed to arrest drivers under the influence. Most checkpoint cases do not involve any evidence of any moving violation.

• Motorists arrested in the Village of Kenmore will be asked to consent to a blood test. The motorist does not have a choice of which chemical test (blood, breath or urine) will be consented to.

• Some motorists are required to appear before a judge for a determination as to what bail, if any, will be required. This is common when the motorist has a history of DUI charges or was considered belligerent by the arresting officer.

• Arrestees who call attorneys at home are typically long-time clients or the friends or relatives of the lawyer. Few lawyers know what questions to ask a caller who wants to know whether it is better to consent or refuse a chemical test. (See "How to handle a wee-hours call," from the Sept. 28, 2007, issue of the Buffalo Law Journal.) The attorney typically has about three minutes to advise the arrestee whether to take the test or not.

• Evaluating DUI charges requires professional case-by-case scrutiny of the client, case, court and consequences.

Aggravating factors

Pursuant to the Erie County district attorney's plea policy, any of the following case factors disqualify defendants from a plea-bargain reduction from DWI (misdemeanor) to DWAI (infraction):

• Motorist is under age 21

• Motorist has a prior DUI conviction

• Motorist had a BAC above .13 percent

• Motorist was involved in an accident

Other aggravating factors include child passengers, a suspended or revoked license, or belligerence toward the arresting officer.

It is not illegal to drive after drinking alcoholic beverages unless you are under the influence. But regardless of the outcome, to drive after drinking risks the ordeal and expense of arrest and prosecution.

My best advice is this: After drinking, use a designated driver.

Buffalo solo practitioner Glenn Murray, a general member of the National College for DUI Defense, can be reached at gemesq@mac.com.